FSA says it has focused supervisory work to be more intensive for firms that pose the biggest risks to the financial system. Photograph Clive Gee/Press Association

The number of risk assessments into financial firms has fallen dramatically since the banking crisis in 2008 when the Financial Services Authority began to shift its approach to supervising the biggest banks in the City. More than 3,750 risk assessments – known as Arrow – have been conducted since 2002, the FSA revealed in response to a Freedom of Information Act request. Some 936 of these took place in 2002, with 616 in 2004 and 427 in 2006. The number then stabilised around 300 until 2008 when it fell to just over 200.

Lyndon Nelson, director of risk management at the FSA, said: "We have increasingly focused our supervisory work to be more intensive and intrusive for those firms that pose the biggest risks to the financial system."

Arrow has become discredited since the banking crisis exposed its shortcomings. Northern Rock was subjected to an assessment every three years, for instance, which the FSA has conceded was too long. When the FSA is disbanded next year, the new Prudential Regulatory Authority will replace Arrow with a five-stage assessment called a PIF (Proactive Intervention Framework). Firms ranked one will be regarded as facing a "low risk" to their viability; five will mean "winding-up under way".

Arrow assessments are still being undertaken, some 43 took place in the first four months of this year and the total is expected to rise to about 200 by year end. Breakdowns between sectors are only available since 2006 and show 29 Arrow reviews were conducted on retail banks in 2007 while just one has taken place in 2011. Of the 28 categories provided by the FSA, the one with the largest number of Arrow assessments between 2006 and the end of Aprill 2011 was among "wholesale and commercial general insurers and reinsurers" with 134.